Third Meeting of the World Federation for Ultrasound In Medicine and Biology

(Scientific Exhibit Section) Brighton, England - July 1982

THE SCIENTIFIC DISCOVERY OF SONIC REFLECTION BY SOFT TISSUES AND APPLICATION OF ULTRASOUND TO DIAGNOSTIC MEDICINE AND TUMOUR SCREENING

J. J, Wild, M.D., Ph.D. (Cantab)

Medico-Technological Research Institute of Minneapolis

Minneapolis, Minnesota, USA

The first scientific proof of sonic energy reflection from within soft tissue histological elements, using "A" mode readout, was reported by Wild in the spring of 1949. Wild, then a visiting English clinical scientist supported by a U.S. Public Health Service surgical fellowship in the Department of Surgery. University of Minnesota, was working on bowel failure. He had previously become Interested In treating bowel distention or bloating at the Miller General Hospital, Greenwich, during World War If when the condition became common, and often fatal, following bomb blast from buzz-bombs. Working with similar surgical bloating conditions In Minneapolis. he needed to measure the changes In thickness of the bowel wall In living, distended patients in order to select the best treatment.

For this purpose, pulse-reflective ultrasound was considered a possibility. Available commercial non-destructive testing equipment developed by Donald Sproule In England and Firestone in the United States for detecting cracks In tank armour plate, operated at too low a frequency to achieve the theoretical resolution required for bowel wall measurement. A much more sophisticated piece of ultrasonic equipment developed during wartime to train flyers to read radar maps of enemy territory lay almost Idle at the Wold-Chamberlain Naval Air Base in Minneapolis, Minnesota. This equipment operated at 15 M/c. Wild gained access to this equipment and with the help of Donald Neal, In technical charge, quickly confirmed the possibility of measurement of living bowel wall thickness at 15 m/c frequency. It was whilst working with Neal standardising the settings of the radar trainer that Wild obtained experimental proof of echo production by gross tissue boundaries such as between fat and meat. More Importantly, proof of echoes coming from within meat itself was also obtained. Further experimenting with a surgical specimen of cancer of the stomach wall brought forth the then completely novel concept, by Wild, of using pulse-echo ultrasound for tumour diagnosis and detection. This concept of the possibility of applying pulseecho ultrasound usefully to medicine was sceptically received by the exact disciplines. The problem seemed to be how to sort out the masses of echoes coming from tissues In terms of precise physical properties and measurements. Wild, a biologist, was thankful that he had observed them at all: that they were there to challenge his ingenuity. No proof of echo production by soft tissues had appeared in the scientific literature up to this time.

Wild and Reid then built a linear "B" mode instrument, a formidable technical task In those days, in order fully to visualise tumours by sweeping from side to side through breast lumps. In May 1953 this instrument produced a real-time image at 15 M/C of a 7mm cancer of the nipple in situ providing direct visual proof of the claimed differential sonic reflection. In 1954 Wild presented his work in a lecture at Middlesex Hospital in London, and to such notables as Prof. Mayneord at the Royal Marsden Hospital and Prof. Chassar Moir at Oxford, catalysing work already in progress. Wild's findings were independently confirmed in Japan in 1956 by Toshio Wagai, et al.

In 1958 Donald, whom Wild had met when he visited England in 1954, published his successes in the "Lancet" with the clinical use of pulse-echo ultrasound In diagnosing gynecological conditions of the abdomen. His technical assistants applied Howry's brilliant technical acoustical work, adaptation of non-real-time radar, and non-destructive testing techniques which had been in progress contemporaneously with Wild and Reid.

BY 1956, Wild and Reid had examined 117 cases of breast pathology with their linear real-time "B" mode instrument and had started work on colon tunour diagnosis and detection. Analysis of the breast series showed very promising results for pre-operative diagnosis. Malignant infiltration of tissues surrounding breast tumours could be resolved at 15 m/c. Most importantly, tumours at the desirable maximum size for a good prognosis (1 cm) were. visualised and tumours as small as 1 mm were seen in the nipple. Breast cysts had been routinely diagnosed as early as 1953.

Wild's early work on soft tissue sonic energy reflection was primary in the field and laid the foundation for present day application and development of clinical ultrasonic techniques, Including echocardiography, ophthalmology, real-time anatomical mapping and tissue characterisation, histological cancer diagnosis, and tumour detection in asymptomatic populations.

Wild is at present following up application of his quantitative technique, which he calls "echometry", to permit operationally efficient cancer detection in the breast and colon. Rapid automatic and complete interrogation of the nipple and glandular breast and of the colon with instantaneous, automatic identification, is essential to successful screening of the asymptornatic population.

Histological diagnosis of overt lesions in traditional medical practice is clinically secondary to the importance of exploiting fully the potential of ultrasound for finding early tumours. Optimum instrument design, the use of high frequency detection equipment and comparative, quantitative techniques give great promise of cost-effective, ultrasonic mass-screening for cancer of the breast and colon.

Empirical biological control techniques were applied by Wild to "tame" the masses of confusing echoes which he found to be coming out of fresh brain specimens containing cancers. Biological control sought to compare normal tissue with abnormal tissue under identical experimental conditions to see if there was any difference; there was. This discovery of brain tumour differentiation has recently been confirmed -- some thirty years after Wild's original, fundamental experiments and clinical demonstration at operation.

More and more proof of differential sonic energy reflection by tumour-disorganised soft tissues was gained by subjective comparison of the graphical time-amplitude ("A" mode) trace pairs obtained from control and diseased tissues. Work at the naval air base was concluded early In 1951 with examination of a clinically nonmalignant nodule and a clinically malignant nodule of the living, Intact human breast. The results were published In the "Lancet" in March 1951. It appeared that it would be possible to diagnose the nature of such lumps since trace pairs of normal and abnormal tissues differed markedly in the malignant nodules; less so In the nonmalignant nodule.

Wild now envisioned the exciting possibility of non-invasive ultrasonic diagnosis and even detection of early cancer at accessible sites. He had two common sites in mind, the breast and the colon. In mid-1950, financed by the National Cancer Institute of the U. S. Public Health Service, Wild and Reid, a recent graduate electrical engineer, had begun working together as an interdisciplinary team. By early 1951 they had built the first hospital "echograph" on wheels and used It at 15 m/c to reveal and to gain increasing subjective clinical evidence of differential sonic energy reflection by neoplastic tissues. Analysis of a series of clinical A-mode records of breast tumours by Wild revealed a statistically valid, objective index of sonic energy return from neoplastic tissue as compared to that of control tissue. This quantitative Index would permit scientific comparison from case to case of differential sonic energy return. At this stage, cancerous tissue seemed to be reflecting more sonic energy than normal surrounding tissue; non-malignant tissue, less.

Application of intensity modulated video traces and sophisticated radar imaging techniques early In 1951 produced direct real-time sector "B" mode images of kidney tissues in the laboratory, followed by clinical application in real-time to breast and other tumours. Real-time gross anatomical cross sectional Images of Wild's arm were obtained by application of this first self-contained small parts scanner. This work was published in a lead article in "Science" in February 1952 (115:226-230), and preceded Howry's first publication of laboratory images by seven months.